Quantum key distribution scheme with orthogonal product states

Abstract

The general conditions for the orthogonal product states of the multistate systems to be used in quantum key distribution (QKD) are proposed, and a novel QKD scheme with orthogonal product states in the $3\times 3$ Hilbert space is presented. We show that this protocol has many distinct features such as great capacity and high efficiency. The generalization to $n\times n$ systems is also discussed and an asymptotic limit of 1/2 for the eavesdropper’s success probability is obtained.